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1/*
2 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
3 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
5 *
6 * This file is part of the Linux kernel and is made available under
7 * the terms of the GNU General Public License, version 2, or at your
8 * option, any later version, incorporated herein by reference.
9 */
10
11#include "autofs_i.h"
12
13static unsigned long now;
14
15/* Check if a dentry can be expired */
16static inline int autofs4_can_expire(struct dentry *dentry,
17 unsigned long timeout, int do_now)
18{
19 struct autofs_info *ino = autofs4_dentry_ino(dentry);
20
21 /* dentry in the process of being deleted */
22 if (ino == NULL)
23 return 0;
24
25 if (!do_now) {
26 /* Too young to die */
27 if (!timeout || time_after(ino->last_used + timeout, now))
28 return 0;
29 }
30 return 1;
31}
32
33/* Check a mount point for busyness */
34static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
35{
36 struct dentry *top = dentry;
37 struct path path = {.mnt = mnt, .dentry = dentry};
38 int status = 1;
39
40 pr_debug("dentry %p %pd\n", dentry, dentry);
41
42 path_get(&path);
43
44 if (!follow_down_one(&path))
45 goto done;
46
47 if (is_autofs4_dentry(path.dentry)) {
48 struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
49
50 /* This is an autofs submount, we can't expire it */
51 if (autofs_type_indirect(sbi->type))
52 goto done;
53 }
54
55 /* Update the expiry counter if fs is busy */
56 if (!may_umount_tree(path.mnt)) {
57 struct autofs_info *ino;
58
59 ino = autofs4_dentry_ino(top);
60 ino->last_used = jiffies;
61 goto done;
62 }
63
64 status = 0;
65done:
66 pr_debug("returning = %d\n", status);
67 path_put(&path);
68 return status;
69}
70
71/*
72 * Calculate and dget next entry in the subdirs list under root.
73 */
74static struct dentry *get_next_positive_subdir(struct dentry *prev,
75 struct dentry *root)
76{
77 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
78 struct list_head *next;
79 struct dentry *q;
80
81 spin_lock(&sbi->lookup_lock);
82 spin_lock(&root->d_lock);
83
84 if (prev)
85 next = prev->d_child.next;
86 else {
87 prev = dget_dlock(root);
88 next = prev->d_subdirs.next;
89 }
90
91cont:
92 if (next == &root->d_subdirs) {
93 spin_unlock(&root->d_lock);
94 spin_unlock(&sbi->lookup_lock);
95 dput(prev);
96 return NULL;
97 }
98
99 q = list_entry(next, struct dentry, d_child);
100
101 spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
102 /* Already gone or negative dentry (under construction) - try next */
103 if (!d_count(q) || !simple_positive(q)) {
104 spin_unlock(&q->d_lock);
105 next = q->d_child.next;
106 goto cont;
107 }
108 dget_dlock(q);
109 spin_unlock(&q->d_lock);
110 spin_unlock(&root->d_lock);
111 spin_unlock(&sbi->lookup_lock);
112
113 dput(prev);
114
115 return q;
116}
117
118/*
119 * Calculate and dget next entry in top down tree traversal.
120 */
121static struct dentry *get_next_positive_dentry(struct dentry *prev,
122 struct dentry *root)
123{
124 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
125 struct list_head *next;
126 struct dentry *p, *ret;
127
128 if (prev == NULL)
129 return dget(root);
130
131 spin_lock(&sbi->lookup_lock);
132relock:
133 p = prev;
134 spin_lock(&p->d_lock);
135again:
136 next = p->d_subdirs.next;
137 if (next == &p->d_subdirs) {
138 while (1) {
139 struct dentry *parent;
140
141 if (p == root) {
142 spin_unlock(&p->d_lock);
143 spin_unlock(&sbi->lookup_lock);
144 dput(prev);
145 return NULL;
146 }
147
148 parent = p->d_parent;
149 if (!spin_trylock(&parent->d_lock)) {
150 spin_unlock(&p->d_lock);
151 cpu_relax();
152 goto relock;
153 }
154 spin_unlock(&p->d_lock);
155 next = p->d_child.next;
156 p = parent;
157 if (next != &parent->d_subdirs)
158 break;
159 }
160 }
161 ret = list_entry(next, struct dentry, d_child);
162
163 spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
164 /* Negative dentry - try next */
165 if (!simple_positive(ret)) {
166 spin_unlock(&p->d_lock);
167 lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_);
168 p = ret;
169 goto again;
170 }
171 dget_dlock(ret);
172 spin_unlock(&ret->d_lock);
173 spin_unlock(&p->d_lock);
174 spin_unlock(&sbi->lookup_lock);
175
176 dput(prev);
177
178 return ret;
179}
180
181/*
182 * Check a direct mount point for busyness.
183 * Direct mounts have similar expiry semantics to tree mounts.
184 * The tree is not busy iff no mountpoints are busy and there are no
185 * autofs submounts.
186 */
187static int autofs4_direct_busy(struct vfsmount *mnt,
188 struct dentry *top,
189 unsigned long timeout,
190 int do_now)
191{
192 pr_debug("top %p %pd\n", top, top);
193
194 /* If it's busy update the expiry counters */
195 if (!may_umount_tree(mnt)) {
196 struct autofs_info *ino;
197
198 ino = autofs4_dentry_ino(top);
199 if (ino)
200 ino->last_used = jiffies;
201 return 1;
202 }
203
204 /* Timeout of a direct mount is determined by its top dentry */
205 if (!autofs4_can_expire(top, timeout, do_now))
206 return 1;
207
208 return 0;
209}
210
211/*
212 * Check a directory tree of mount points for busyness
213 * The tree is not busy iff no mountpoints are busy
214 */
215static int autofs4_tree_busy(struct vfsmount *mnt,
216 struct dentry *top,
217 unsigned long timeout,
218 int do_now)
219{
220 struct autofs_info *top_ino = autofs4_dentry_ino(top);
221 struct dentry *p;
222
223 pr_debug("top %p %pd\n", top, top);
224
225 /* Negative dentry - give up */
226 if (!simple_positive(top))
227 return 1;
228
229 p = NULL;
230 while ((p = get_next_positive_dentry(p, top))) {
231 pr_debug("dentry %p %pd\n", p, p);
232
233 /*
234 * Is someone visiting anywhere in the subtree ?
235 * If there's no mount we need to check the usage
236 * count for the autofs dentry.
237 * If the fs is busy update the expiry counter.
238 */
239 if (d_mountpoint(p)) {
240 if (autofs4_mount_busy(mnt, p)) {
241 top_ino->last_used = jiffies;
242 dput(p);
243 return 1;
244 }
245 } else {
246 struct autofs_info *ino = autofs4_dentry_ino(p);
247 unsigned int ino_count = atomic_read(&ino->count);
248
249 /* allow for dget above and top is already dgot */
250 if (p == top)
251 ino_count += 2;
252 else
253 ino_count++;
254
255 if (d_count(p) > ino_count) {
256 top_ino->last_used = jiffies;
257 dput(p);
258 return 1;
259 }
260 }
261 }
262
263 /* Timeout of a tree mount is ultimately determined by its top dentry */
264 if (!autofs4_can_expire(top, timeout, do_now))
265 return 1;
266
267 return 0;
268}
269
270static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
271 struct dentry *parent,
272 unsigned long timeout,
273 int do_now)
274{
275 struct dentry *p;
276
277 pr_debug("parent %p %pd\n", parent, parent);
278
279 p = NULL;
280 while ((p = get_next_positive_dentry(p, parent))) {
281 pr_debug("dentry %p %pd\n", p, p);
282
283 if (d_mountpoint(p)) {
284 /* Can we umount this guy */
285 if (autofs4_mount_busy(mnt, p))
286 continue;
287
288 /* Can we expire this guy */
289 if (autofs4_can_expire(p, timeout, do_now))
290 return p;
291 }
292 }
293 return NULL;
294}
295
296/* Check if we can expire a direct mount (possibly a tree) */
297struct dentry *autofs4_expire_direct(struct super_block *sb,
298 struct vfsmount *mnt,
299 struct autofs_sb_info *sbi,
300 int how)
301{
302 unsigned long timeout;
303 struct dentry *root = dget(sb->s_root);
304 int do_now = how & AUTOFS_EXP_IMMEDIATE;
305 struct autofs_info *ino;
306
307 if (!root)
308 return NULL;
309
310 now = jiffies;
311 timeout = sbi->exp_timeout;
312
313 spin_lock(&sbi->fs_lock);
314 ino = autofs4_dentry_ino(root);
315 /* No point expiring a pending mount */
316 if (ino->flags & AUTOFS_INF_PENDING)
317 goto out;
318 if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
319 ino->flags |= AUTOFS_INF_NO_RCU;
320 spin_unlock(&sbi->fs_lock);
321 synchronize_rcu();
322 spin_lock(&sbi->fs_lock);
323 if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
324 ino->flags |= AUTOFS_INF_EXPIRING;
325 smp_mb();
326 ino->flags &= ~AUTOFS_INF_NO_RCU;
327 init_completion(&ino->expire_complete);
328 spin_unlock(&sbi->fs_lock);
329 return root;
330 }
331 ino->flags &= ~AUTOFS_INF_NO_RCU;
332 }
333out:
334 spin_unlock(&sbi->fs_lock);
335 dput(root);
336
337 return NULL;
338}
339
340/* Check if 'dentry' should expire, or return a nearby
341 * dentry that is suitable.
342 * If returned dentry is different from arg dentry,
343 * then a dget() reference was taken, else not.
344 */
345static struct dentry *should_expire(struct dentry *dentry,
346 struct vfsmount *mnt,
347 unsigned long timeout,
348 int how)
349{
350 int do_now = how & AUTOFS_EXP_IMMEDIATE;
351 int exp_leaves = how & AUTOFS_EXP_LEAVES;
352 struct autofs_info *ino = autofs4_dentry_ino(dentry);
353 unsigned int ino_count;
354
355 /* No point expiring a pending mount */
356 if (ino->flags & AUTOFS_INF_PENDING)
357 return NULL;
358
359 /*
360 * Case 1: (i) indirect mount or top level pseudo direct mount
361 * (autofs-4.1).
362 * (ii) indirect mount with offset mount, check the "/"
363 * offset (autofs-5.0+).
364 */
365 if (d_mountpoint(dentry)) {
366 pr_debug("checking mountpoint %p %pd\n", dentry, dentry);
367
368 /* Can we umount this guy */
369 if (autofs4_mount_busy(mnt, dentry))
370 return NULL;
371
372 /* Can we expire this guy */
373 if (autofs4_can_expire(dentry, timeout, do_now))
374 return dentry;
375 return NULL;
376 }
377
378 if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
379 pr_debug("checking symlink %p %pd\n", dentry, dentry);
380 /*
381 * A symlink can't be "busy" in the usual sense so
382 * just check last used for expire timeout.
383 */
384 if (autofs4_can_expire(dentry, timeout, do_now))
385 return dentry;
386 return NULL;
387 }
388
389 if (simple_empty(dentry))
390 return NULL;
391
392 /* Case 2: tree mount, expire iff entire tree is not busy */
393 if (!exp_leaves) {
394 /* Path walk currently on this dentry? */
395 ino_count = atomic_read(&ino->count) + 1;
396 if (d_count(dentry) > ino_count)
397 return NULL;
398
399 if (!autofs4_tree_busy(mnt, dentry, timeout, do_now))
400 return dentry;
401 /*
402 * Case 3: pseudo direct mount, expire individual leaves
403 * (autofs-4.1).
404 */
405 } else {
406 /* Path walk currently on this dentry? */
407 struct dentry *expired;
408
409 ino_count = atomic_read(&ino->count) + 1;
410 if (d_count(dentry) > ino_count)
411 return NULL;
412
413 expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
414 if (expired) {
415 if (expired == dentry)
416 dput(dentry);
417 return expired;
418 }
419 }
420 return NULL;
421}
422/*
423 * Find an eligible tree to time-out
424 * A tree is eligible if :-
425 * - it is unused by any user process
426 * - it has been unused for exp_timeout time
427 */
428struct dentry *autofs4_expire_indirect(struct super_block *sb,
429 struct vfsmount *mnt,
430 struct autofs_sb_info *sbi,
431 int how)
432{
433 unsigned long timeout;
434 struct dentry *root = sb->s_root;
435 struct dentry *dentry;
436 struct dentry *expired;
437 struct autofs_info *ino;
438
439 if (!root)
440 return NULL;
441
442 now = jiffies;
443 timeout = sbi->exp_timeout;
444
445 dentry = NULL;
446 while ((dentry = get_next_positive_subdir(dentry, root))) {
447 spin_lock(&sbi->fs_lock);
448 ino = autofs4_dentry_ino(dentry);
449 if (ino->flags & AUTOFS_INF_NO_RCU)
450 expired = NULL;
451 else
452 expired = should_expire(dentry, mnt, timeout, how);
453 if (!expired) {
454 spin_unlock(&sbi->fs_lock);
455 continue;
456 }
457 ino = autofs4_dentry_ino(expired);
458 ino->flags |= AUTOFS_INF_NO_RCU;
459 spin_unlock(&sbi->fs_lock);
460 synchronize_rcu();
461 spin_lock(&sbi->fs_lock);
462 if (should_expire(expired, mnt, timeout, how)) {
463 if (expired != dentry)
464 dput(dentry);
465 goto found;
466 }
467
468 ino->flags &= ~AUTOFS_INF_NO_RCU;
469 if (expired != dentry)
470 dput(expired);
471 spin_unlock(&sbi->fs_lock);
472 }
473 return NULL;
474
475found:
476 pr_debug("returning %p %pd\n", expired, expired);
477 ino->flags |= AUTOFS_INF_EXPIRING;
478 smp_mb();
479 ino->flags &= ~AUTOFS_INF_NO_RCU;
480 init_completion(&ino->expire_complete);
481 spin_unlock(&sbi->fs_lock);
482 spin_lock(&sbi->lookup_lock);
483 spin_lock(&expired->d_parent->d_lock);
484 spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
485 list_move(&expired->d_parent->d_subdirs, &expired->d_child);
486 spin_unlock(&expired->d_lock);
487 spin_unlock(&expired->d_parent->d_lock);
488 spin_unlock(&sbi->lookup_lock);
489 return expired;
490}
491
492int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
493{
494 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
495 struct autofs_info *ino = autofs4_dentry_ino(dentry);
496 int status;
497
498 /* Block on any pending expire */
499 if (!(ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU)))
500 return 0;
501 if (rcu_walk)
502 return -ECHILD;
503
504 spin_lock(&sbi->fs_lock);
505 if (ino->flags & AUTOFS_INF_EXPIRING) {
506 spin_unlock(&sbi->fs_lock);
507
508 pr_debug("waiting for expire %p name=%pd\n", dentry, dentry);
509
510 status = autofs4_wait(sbi, dentry, NFY_NONE);
511 wait_for_completion(&ino->expire_complete);
512
513 pr_debug("expire done status=%d\n", status);
514
515 if (d_unhashed(dentry))
516 return -EAGAIN;
517
518 return status;
519 }
520 spin_unlock(&sbi->fs_lock);
521
522 return 0;
523}
524
525/* Perform an expiry operation */
526int autofs4_expire_run(struct super_block *sb,
527 struct vfsmount *mnt,
528 struct autofs_sb_info *sbi,
529 struct autofs_packet_expire __user *pkt_p)
530{
531 struct autofs_packet_expire pkt;
532 struct autofs_info *ino;
533 struct dentry *dentry;
534 int ret = 0;
535
536 memset(&pkt, 0, sizeof(pkt));
537
538 pkt.hdr.proto_version = sbi->version;
539 pkt.hdr.type = autofs_ptype_expire;
540
541 dentry = autofs4_expire_indirect(sb, mnt, sbi, 0);
542 if (!dentry)
543 return -EAGAIN;
544
545 pkt.len = dentry->d_name.len;
546 memcpy(pkt.name, dentry->d_name.name, pkt.len);
547 pkt.name[pkt.len] = '\0';
548 dput(dentry);
549
550 if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
551 ret = -EFAULT;
552
553 spin_lock(&sbi->fs_lock);
554 ino = autofs4_dentry_ino(dentry);
555 /* avoid rapid-fire expire attempts if expiry fails */
556 ino->last_used = now;
557 ino->flags &= ~AUTOFS_INF_EXPIRING;
558 complete_all(&ino->expire_complete);
559 spin_unlock(&sbi->fs_lock);
560
561 return ret;
562}
563
564int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
565 struct autofs_sb_info *sbi, int when)
566{
567 struct dentry *dentry;
568 int ret = -EAGAIN;
569
570 if (autofs_type_trigger(sbi->type))
571 dentry = autofs4_expire_direct(sb, mnt, sbi, when);
572 else
573 dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
574
575 if (dentry) {
576 struct autofs_info *ino = autofs4_dentry_ino(dentry);
577
578 /* This is synchronous because it makes the daemon a
579 * little easier
580 */
581 ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
582
583 spin_lock(&sbi->fs_lock);
584 /* avoid rapid-fire expire attempts if expiry fails */
585 ino->last_used = now;
586 ino->flags &= ~AUTOFS_INF_EXPIRING;
587 complete_all(&ino->expire_complete);
588 spin_unlock(&sbi->fs_lock);
589 dput(dentry);
590 }
591
592 return ret;
593}
594
595/*
596 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
597 * more to be done.
598 */
599int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
600 struct autofs_sb_info *sbi, int __user *arg)
601{
602 int do_now = 0;
603
604 if (arg && get_user(do_now, arg))
605 return -EFAULT;
606
607 return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
608}
609
1/* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/expire.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
7 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
8 *
9 * This file is part of the Linux kernel and is made available under
10 * the terms of the GNU General Public License, version 2, or at your
11 * option, any later version, incorporated herein by reference.
12 *
13 * ------------------------------------------------------------------------- */
14
15#include "autofs_i.h"
16
17static unsigned long now;
18
19/* Check if a dentry can be expired */
20static inline int autofs4_can_expire(struct dentry *dentry,
21 unsigned long timeout, int do_now)
22{
23 struct autofs_info *ino = autofs4_dentry_ino(dentry);
24
25 /* dentry in the process of being deleted */
26 if (ino == NULL)
27 return 0;
28
29 if (!do_now) {
30 /* Too young to die */
31 if (!timeout || time_after(ino->last_used + timeout, now))
32 return 0;
33
34 /* update last_used here :-
35 - obviously makes sense if it is in use now
36 - less obviously, prevents rapid-fire expire
37 attempts if expire fails the first time */
38 ino->last_used = now;
39 }
40 return 1;
41}
42
43/* Check a mount point for busyness */
44static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
45{
46 struct dentry *top = dentry;
47 struct path path = {.mnt = mnt, .dentry = dentry};
48 int status = 1;
49
50 DPRINTK("dentry %p %.*s",
51 dentry, (int)dentry->d_name.len, dentry->d_name.name);
52
53 path_get(&path);
54
55 if (!follow_down_one(&path))
56 goto done;
57
58 if (is_autofs4_dentry(path.dentry)) {
59 struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
60
61 /* This is an autofs submount, we can't expire it */
62 if (autofs_type_indirect(sbi->type))
63 goto done;
64
65 /*
66 * Otherwise it's an offset mount and we need to check
67 * if we can umount its mount, if there is one.
68 */
69 if (!d_mountpoint(path.dentry)) {
70 status = 0;
71 goto done;
72 }
73 }
74
75 /* Update the expiry counter if fs is busy */
76 if (!may_umount_tree(path.mnt)) {
77 struct autofs_info *ino = autofs4_dentry_ino(top);
78 ino->last_used = jiffies;
79 goto done;
80 }
81
82 status = 0;
83done:
84 DPRINTK("returning = %d", status);
85 path_put(&path);
86 return status;
87}
88
89/*
90 * Calculate and dget next entry in the subdirs list under root.
91 */
92static struct dentry *get_next_positive_subdir(struct dentry *prev,
93 struct dentry *root)
94{
95 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
96 struct list_head *next;
97 struct dentry *p, *q;
98
99 spin_lock(&sbi->lookup_lock);
100
101 if (prev == NULL) {
102 spin_lock(&root->d_lock);
103 prev = dget_dlock(root);
104 next = prev->d_subdirs.next;
105 p = prev;
106 goto start;
107 }
108
109 p = prev;
110 spin_lock(&p->d_lock);
111again:
112 next = p->d_u.d_child.next;
113start:
114 if (next == &root->d_subdirs) {
115 spin_unlock(&p->d_lock);
116 spin_unlock(&sbi->lookup_lock);
117 dput(prev);
118 return NULL;
119 }
120
121 q = list_entry(next, struct dentry, d_u.d_child);
122
123 spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
124 /* Negative dentry - try next */
125 if (!simple_positive(q)) {
126 spin_unlock(&p->d_lock);
127 p = q;
128 goto again;
129 }
130 dget_dlock(q);
131 spin_unlock(&q->d_lock);
132 spin_unlock(&p->d_lock);
133 spin_unlock(&sbi->lookup_lock);
134
135 dput(prev);
136
137 return q;
138}
139
140/*
141 * Calculate and dget next entry in top down tree traversal.
142 */
143static struct dentry *get_next_positive_dentry(struct dentry *prev,
144 struct dentry *root)
145{
146 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
147 struct list_head *next;
148 struct dentry *p, *ret;
149
150 if (prev == NULL)
151 return dget(root);
152
153 spin_lock(&sbi->lookup_lock);
154relock:
155 p = prev;
156 spin_lock(&p->d_lock);
157again:
158 next = p->d_subdirs.next;
159 if (next == &p->d_subdirs) {
160 while (1) {
161 struct dentry *parent;
162
163 if (p == root) {
164 spin_unlock(&p->d_lock);
165 spin_unlock(&sbi->lookup_lock);
166 dput(prev);
167 return NULL;
168 }
169
170 parent = p->d_parent;
171 if (!spin_trylock(&parent->d_lock)) {
172 spin_unlock(&p->d_lock);
173 cpu_relax();
174 goto relock;
175 }
176 spin_unlock(&p->d_lock);
177 next = p->d_u.d_child.next;
178 p = parent;
179 if (next != &parent->d_subdirs)
180 break;
181 }
182 }
183 ret = list_entry(next, struct dentry, d_u.d_child);
184
185 spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
186 /* Negative dentry - try next */
187 if (!simple_positive(ret)) {
188 spin_unlock(&p->d_lock);
189 p = ret;
190 goto again;
191 }
192 dget_dlock(ret);
193 spin_unlock(&ret->d_lock);
194 spin_unlock(&p->d_lock);
195 spin_unlock(&sbi->lookup_lock);
196
197 dput(prev);
198
199 return ret;
200}
201
202/*
203 * Check a direct mount point for busyness.
204 * Direct mounts have similar expiry semantics to tree mounts.
205 * The tree is not busy iff no mountpoints are busy and there are no
206 * autofs submounts.
207 */
208static int autofs4_direct_busy(struct vfsmount *mnt,
209 struct dentry *top,
210 unsigned long timeout,
211 int do_now)
212{
213 DPRINTK("top %p %.*s",
214 top, (int) top->d_name.len, top->d_name.name);
215
216 /* If it's busy update the expiry counters */
217 if (!may_umount_tree(mnt)) {
218 struct autofs_info *ino = autofs4_dentry_ino(top);
219 if (ino)
220 ino->last_used = jiffies;
221 return 1;
222 }
223
224 /* Timeout of a direct mount is determined by its top dentry */
225 if (!autofs4_can_expire(top, timeout, do_now))
226 return 1;
227
228 return 0;
229}
230
231/* Check a directory tree of mount points for busyness
232 * The tree is not busy iff no mountpoints are busy
233 */
234static int autofs4_tree_busy(struct vfsmount *mnt,
235 struct dentry *top,
236 unsigned long timeout,
237 int do_now)
238{
239 struct autofs_info *top_ino = autofs4_dentry_ino(top);
240 struct dentry *p;
241
242 DPRINTK("top %p %.*s",
243 top, (int)top->d_name.len, top->d_name.name);
244
245 /* Negative dentry - give up */
246 if (!simple_positive(top))
247 return 1;
248
249 p = NULL;
250 while ((p = get_next_positive_dentry(p, top))) {
251 DPRINTK("dentry %p %.*s",
252 p, (int) p->d_name.len, p->d_name.name);
253
254 /*
255 * Is someone visiting anywhere in the subtree ?
256 * If there's no mount we need to check the usage
257 * count for the autofs dentry.
258 * If the fs is busy update the expiry counter.
259 */
260 if (d_mountpoint(p)) {
261 if (autofs4_mount_busy(mnt, p)) {
262 top_ino->last_used = jiffies;
263 dput(p);
264 return 1;
265 }
266 } else {
267 struct autofs_info *ino = autofs4_dentry_ino(p);
268 unsigned int ino_count = atomic_read(&ino->count);
269
270 /*
271 * Clean stale dentries below that have not been
272 * invalidated after a mount fail during lookup
273 */
274 d_invalidate(p);
275
276 /* allow for dget above and top is already dgot */
277 if (p == top)
278 ino_count += 2;
279 else
280 ino_count++;
281
282 if (p->d_count > ino_count) {
283 top_ino->last_used = jiffies;
284 dput(p);
285 return 1;
286 }
287 }
288 }
289
290 /* Timeout of a tree mount is ultimately determined by its top dentry */
291 if (!autofs4_can_expire(top, timeout, do_now))
292 return 1;
293
294 return 0;
295}
296
297static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
298 struct dentry *parent,
299 unsigned long timeout,
300 int do_now)
301{
302 struct dentry *p;
303
304 DPRINTK("parent %p %.*s",
305 parent, (int)parent->d_name.len, parent->d_name.name);
306
307 p = NULL;
308 while ((p = get_next_positive_dentry(p, parent))) {
309 DPRINTK("dentry %p %.*s",
310 p, (int) p->d_name.len, p->d_name.name);
311
312 if (d_mountpoint(p)) {
313 /* Can we umount this guy */
314 if (autofs4_mount_busy(mnt, p))
315 continue;
316
317 /* Can we expire this guy */
318 if (autofs4_can_expire(p, timeout, do_now))
319 return p;
320 }
321 }
322 return NULL;
323}
324
325/* Check if we can expire a direct mount (possibly a tree) */
326struct dentry *autofs4_expire_direct(struct super_block *sb,
327 struct vfsmount *mnt,
328 struct autofs_sb_info *sbi,
329 int how)
330{
331 unsigned long timeout;
332 struct dentry *root = dget(sb->s_root);
333 int do_now = how & AUTOFS_EXP_IMMEDIATE;
334 struct autofs_info *ino;
335
336 if (!root)
337 return NULL;
338
339 now = jiffies;
340 timeout = sbi->exp_timeout;
341
342 spin_lock(&sbi->fs_lock);
343 ino = autofs4_dentry_ino(root);
344 /* No point expiring a pending mount */
345 if (ino->flags & AUTOFS_INF_PENDING)
346 goto out;
347 if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
348 struct autofs_info *ino = autofs4_dentry_ino(root);
349 ino->flags |= AUTOFS_INF_EXPIRING;
350 init_completion(&ino->expire_complete);
351 spin_unlock(&sbi->fs_lock);
352 return root;
353 }
354out:
355 spin_unlock(&sbi->fs_lock);
356 dput(root);
357
358 return NULL;
359}
360
361/*
362 * Find an eligible tree to time-out
363 * A tree is eligible if :-
364 * - it is unused by any user process
365 * - it has been unused for exp_timeout time
366 */
367struct dentry *autofs4_expire_indirect(struct super_block *sb,
368 struct vfsmount *mnt,
369 struct autofs_sb_info *sbi,
370 int how)
371{
372 unsigned long timeout;
373 struct dentry *root = sb->s_root;
374 struct dentry *dentry;
375 struct dentry *expired = NULL;
376 int do_now = how & AUTOFS_EXP_IMMEDIATE;
377 int exp_leaves = how & AUTOFS_EXP_LEAVES;
378 struct autofs_info *ino;
379 unsigned int ino_count;
380
381 if (!root)
382 return NULL;
383
384 now = jiffies;
385 timeout = sbi->exp_timeout;
386
387 dentry = NULL;
388 while ((dentry = get_next_positive_subdir(dentry, root))) {
389 spin_lock(&sbi->fs_lock);
390 ino = autofs4_dentry_ino(dentry);
391 /* No point expiring a pending mount */
392 if (ino->flags & AUTOFS_INF_PENDING)
393 goto next;
394
395 /*
396 * Case 1: (i) indirect mount or top level pseudo direct mount
397 * (autofs-4.1).
398 * (ii) indirect mount with offset mount, check the "/"
399 * offset (autofs-5.0+).
400 */
401 if (d_mountpoint(dentry)) {
402 DPRINTK("checking mountpoint %p %.*s",
403 dentry, (int)dentry->d_name.len, dentry->d_name.name);
404
405 /* Path walk currently on this dentry? */
406 ino_count = atomic_read(&ino->count) + 2;
407 if (dentry->d_count > ino_count)
408 goto next;
409
410 /* Can we umount this guy */
411 if (autofs4_mount_busy(mnt, dentry))
412 goto next;
413
414 /* Can we expire this guy */
415 if (autofs4_can_expire(dentry, timeout, do_now)) {
416 expired = dentry;
417 goto found;
418 }
419 goto next;
420 }
421
422 if (simple_empty(dentry))
423 goto next;
424
425 /* Case 2: tree mount, expire iff entire tree is not busy */
426 if (!exp_leaves) {
427 /* Path walk currently on this dentry? */
428 ino_count = atomic_read(&ino->count) + 1;
429 if (dentry->d_count > ino_count)
430 goto next;
431
432 if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
433 expired = dentry;
434 goto found;
435 }
436 /*
437 * Case 3: pseudo direct mount, expire individual leaves
438 * (autofs-4.1).
439 */
440 } else {
441 /* Path walk currently on this dentry? */
442 ino_count = atomic_read(&ino->count) + 1;
443 if (dentry->d_count > ino_count)
444 goto next;
445
446 expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
447 if (expired) {
448 dput(dentry);
449 goto found;
450 }
451 }
452next:
453 spin_unlock(&sbi->fs_lock);
454 }
455 return NULL;
456
457found:
458 DPRINTK("returning %p %.*s",
459 expired, (int)expired->d_name.len, expired->d_name.name);
460 ino = autofs4_dentry_ino(expired);
461 ino->flags |= AUTOFS_INF_EXPIRING;
462 init_completion(&ino->expire_complete);
463 spin_unlock(&sbi->fs_lock);
464 spin_lock(&sbi->lookup_lock);
465 spin_lock(&expired->d_parent->d_lock);
466 spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
467 list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
468 spin_unlock(&expired->d_lock);
469 spin_unlock(&expired->d_parent->d_lock);
470 spin_unlock(&sbi->lookup_lock);
471 return expired;
472}
473
474int autofs4_expire_wait(struct dentry *dentry)
475{
476 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
477 struct autofs_info *ino = autofs4_dentry_ino(dentry);
478 int status;
479
480 /* Block on any pending expire */
481 spin_lock(&sbi->fs_lock);
482 if (ino->flags & AUTOFS_INF_EXPIRING) {
483 spin_unlock(&sbi->fs_lock);
484
485 DPRINTK("waiting for expire %p name=%.*s",
486 dentry, dentry->d_name.len, dentry->d_name.name);
487
488 status = autofs4_wait(sbi, dentry, NFY_NONE);
489 wait_for_completion(&ino->expire_complete);
490
491 DPRINTK("expire done status=%d", status);
492
493 if (d_unhashed(dentry))
494 return -EAGAIN;
495
496 return status;
497 }
498 spin_unlock(&sbi->fs_lock);
499
500 return 0;
501}
502
503/* Perform an expiry operation */
504int autofs4_expire_run(struct super_block *sb,
505 struct vfsmount *mnt,
506 struct autofs_sb_info *sbi,
507 struct autofs_packet_expire __user *pkt_p)
508{
509 struct autofs_packet_expire pkt;
510 struct autofs_info *ino;
511 struct dentry *dentry;
512 int ret = 0;
513
514 memset(&pkt,0,sizeof pkt);
515
516 pkt.hdr.proto_version = sbi->version;
517 pkt.hdr.type = autofs_ptype_expire;
518
519 if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
520 return -EAGAIN;
521
522 pkt.len = dentry->d_name.len;
523 memcpy(pkt.name, dentry->d_name.name, pkt.len);
524 pkt.name[pkt.len] = '\0';
525 dput(dentry);
526
527 if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
528 ret = -EFAULT;
529
530 spin_lock(&sbi->fs_lock);
531 ino = autofs4_dentry_ino(dentry);
532 ino->flags &= ~AUTOFS_INF_EXPIRING;
533 complete_all(&ino->expire_complete);
534 spin_unlock(&sbi->fs_lock);
535
536 return ret;
537}
538
539int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
540 struct autofs_sb_info *sbi, int when)
541{
542 struct dentry *dentry;
543 int ret = -EAGAIN;
544
545 if (autofs_type_trigger(sbi->type))
546 dentry = autofs4_expire_direct(sb, mnt, sbi, when);
547 else
548 dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
549
550 if (dentry) {
551 struct autofs_info *ino = autofs4_dentry_ino(dentry);
552
553 /* This is synchronous because it makes the daemon a
554 little easier */
555 ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
556
557 spin_lock(&sbi->fs_lock);
558 ino->flags &= ~AUTOFS_INF_EXPIRING;
559 spin_lock(&dentry->d_lock);
560 if (!ret) {
561 if ((IS_ROOT(dentry) ||
562 (autofs_type_indirect(sbi->type) &&
563 IS_ROOT(dentry->d_parent))) &&
564 !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
565 __managed_dentry_set_automount(dentry);
566 }
567 spin_unlock(&dentry->d_lock);
568 complete_all(&ino->expire_complete);
569 spin_unlock(&sbi->fs_lock);
570 dput(dentry);
571 }
572
573 return ret;
574}
575
576/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
577 more to be done */
578int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
579 struct autofs_sb_info *sbi, int __user *arg)
580{
581 int do_now = 0;
582
583 if (arg && get_user(do_now, arg))
584 return -EFAULT;
585
586 return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
587}
588